Genetically Modified Mosquitoes: What does this mean to the population?

Mosquitoes are one of those insects which have caused a lot of havoc in communities and societies. This insect not only has a painful bite but also through the bite, it transmits some of the most dangerous infectious diseases on the planet. Not all mosquitoes transmit diseases.

Scientifically living things are classified or grouped systematically for easy identification and comparison with other living things just as we humans use names, and other unique features to identify ourselves.  As such if we use our day to day scenario, every living thing belongs to a clan, and in this clan there are families, and each family is known by its own name (surname) and then the families have children or offspring, who have their own unique names. Scientifically living things are also classified in a similar manner, each plant or animal belongs to a “clan” know as a FAMILY, and the “families” in the “clan” are known as GENUS, which like the “surname” of the family  and the “unique names” of the children and offspring is what is known as SPECIES. So when we say that malaria is caused by the parasite Plasmodium falciparum,  all we are trying to say is that the parasite belongs to the GENUS- Plasmodium and the SPECIES falciparum.

The reason why I had to take you back to this systematic class of biology, where we learn how living things are classified, is because today’s article will involve some of these terminologies that I just introduced.

As I mentioned earlier, some mosquitoes transmit diseases which are and have been big Public health problems.  When it comes to diseases in the tropics and subtropical regions, mosquitoes from the genus Aedes and Anopheles transmit some of the most dangerous infectious diseases in the world.

Some of the species of Aedes transmit Dengue fever, yellow fever, and human lymphatic filariasis.  Aedes aegypti causes yellow fever and a lot of research has been done to understand this mosquito. With the advancement in technology, scientists have sequenced the DNA (which contains all the information of how and what a living thing is made up of (Genome)) from these mosquitoes in order to find ways and means to understand them better and also how they carry and transmit these diseases.

Anopheles is another genus of mosquitoes which is well known with transmission of diseases. Of the 460 known species of Anopheles, 100 can transmit human malaria. Anopheles are vectors (transmit the parasites, bacteria, viruses,and worms which cause disease) for canine heart worm, Wuchureria bancrofti (which causes filariasis), Brugia malayi and viruses e.g. those that cause O’nyong’nyong fever.

Just as Aedes aegypti, the sequence for Anopheles gambie genome, the worlds most important malaria vector has been published.

As technology is advancing by the day, hour, minute, scientists have and are working hard manipulating the genomes of sequenced vectors in order to stop them from transmitting the diseases. The genetic manipulations also known as genetic modifications involve playing around with parts of the genome in order to either sterilize the vector, stop the vector from further reproduction (suicide genes) and many more.

Some weeks back there was a story where a biotech company has released genetically modified mosquitoes into the environment. These mosquitoes carry a “suicide” gene where if they mate with the female mosquitoes they will not be able to produce offspring and the mosquito population will die out. As simple as it sounds the consequences in the long term are unknown and that is where the danger is.

Most of the genetic modifications are done in controlled environments in laboratories, where these experimental animals are monitored. But when these insects are released in the environment we have no idea, what mutations (changes in the DNA which may result in changes in behavior of a plant or animal) may come up.  How will the companies monitor or follow these mosquitoes once released? Are they tagged so that they could easily trace their movements? Flying insects can easily cross borders into other regions is there any awareness in the communities where the mosquitoes have been released and the neighbouring communities which could be victims of these mosquitoes? What dangers do these genetically modified mosquitoes present to society?

What are the long term effects?

There are many questions we can ask.

Is it worth it to have these genetically modified insects released in our societies when we don’t fully know the consequences they will have in our environments? Yes we have diseases which are killing our populations and we are desperate to get rid of them, but is this the right way? Are we not adding another complicated problem on top of an already existing problem?

I am not against advances in science but let us not use desperate situations as a reason to try out unfinished products. Developing countries have been a dumping ground of many experiments whose long term effects are unknown. Infectious diseases are already causing havoc in developing countries let us not add more problems, but let us find ways to solve these problems.

Have your say, I would like to hear your opinions on this.

Can Stigma be Conquered?

The first time I heard of the word stigma was at the onset of the HIV/AIDS pandemic. This word was everywhere, on the radio, in newspapers, in brochures and posters but I did not understand what it meant.

With time I began to get the idea what this word was all about. It was a word that brought fear in every one who was HIV positive and to those who were not sure whether they had the disease or not.

So what is stigma?

AIDS-related stigma and discrimination is described as prejudice, negative attitudes, abuse and maltreatment directed at people living with HIV and AIDS.

Different societies and cultures have shown varying levels of stigma and discrimination and these in turn have instilled fear in people of being discriminated against. This fear has resulted in people running away from knowing their HIV status and disclosing their HIV status if they know it.

Governments and non-governmental organizations are working hand in hand with many African countries where the disease has caused a lot of havoc, to bring awareness on the disease.

In the beginning it was not easy to break the cultural barriers and talk about issues concerning sexuality which are considered as taboo. But as the disease claimed more lives and infections sky rocketed people resorted to opening up and bringing the truth about HIV/AIDS into the open. HIV/AIDS has created thousands and thousands of orphans in Africa and as such communities are working hard to bring awareness of the disease to both young and old.  In Malawi for example, children in primary school (between the age of 5 and 12) and in secondary school (12-18years of age) are taught about the danger of HIV/AIDS and how they can contract it as well as avoid infection. In the rural areas, health personnel and social workers are working hard to bring awareness on HIV/AIDS.

But how has this awareness affected the issues of stigma and discrimination in these societies?

Uganda was badly hit by the pandemic but the country embarked on huge HIV/AIDS awareness campaign which showed remarkable results in the society, their perception of the disease as well as stigma and discrimination.

In Malawi, I noticed that people are more open to talk about their HIV status, they are also open to tell their friends and family members to go for HIV testing if they suspect the disease. The interesting thing that I noted was people will say “ it is better to go and get these free medication and stay alive than hide the disease and die from it”. This attitude has helped many people to come in the open and get treatment. There are still some who do not want to know their HIV status and even if they see all the symptoms leading to HIV/AIDS they would still deny being tested.

A study in Botswana showed that stigmatising attitudes lessened three years after the introduction of the national program providing access to treatment.  A reduction in stigma was also observed in Tanzania with the introduction of the antiretroviral treatment (ART).

The Secretary general of the UN, Ban Ki Moon said and I quote “ Stigma remains a single most important barrier to public action. It is a main reason why too many people are afraid to see a doctor to determine whether they have the disease, or to seek treatment if so. It helps make AIDS the silent killer, because people fear social disgrace, of speaking about it, or taking easily available precautions. Stigma is a chief reason why the AIDS epidemic continues to devastate societies around the world.”

So can stigma be conquered? I believe the answer lies with each and every one of us. If we have to fight the HIV/AIDS pandemic, we need to work together against stigma and discrimination.

Control of Zoonotic Diseases

Due to the increase in incidence of zoonotic diseases around the world, efforts have been made and are still being made to control zoonotic diseases.

Since zoonoses involve both humans and animals, efforts to control the diseases require working both with the health and veterinary sector. In as much as these two sectors have to work hand in hand, there is a very important aspect that we also have to consider in order to control these diseases, that is the communities involved.

In the past efforts have been done to control many infectious diseases but unfortunately the most crucial part is always left out until the last minute. Community involvement has always been left out until the last minute when an epidemic has hit or when there is an outbreak. Unfortunately when the disease has been controlled it is all forgotten. There is therefore need for continuity in community involvement to achieve effective control of zoonoses.

With zoonoses being spread from animal to humans through meat, animal products and animal excreta from both wild and domesticated animals, we have to go down to the grass roots, that is the people who live in close proximity with wild and domesticated animals. But who are the people likely to be in close proximity with these animals? These could be farmers, people who live within or in close proximity with rainforests, people working in arbatoires, cattle herders, bush hunters, park rangers, zoo keepers the list is endless. Apart from people who live in close proximity with animals, let us consider also those that consume meat and meat products.

As outlined above apart from experts from the health and veterinary, it is important to involve the community if efforts to control zoonoses have to succeed. How?

Step1:

Through surveillance of food sources in the villages and communities, this includes where they slaughter both their wild and domesticated animals, where they hunt, and most important to test the meat for diseases before it is consumed. In most developing countries, there are communities that are either isolated or have no facilities and or expertise to monitor and or test the meat for diseases. This is an important step as this could be a crucial step in controlling some of the zoonoses.

 Step2:

Knowledge and understanding of their eating and food storage habits, how does the community prepare their meat products, do they eat the meat raw, how do they handle the meat after slaughter?

This step is crucial in understanding where the source of the disease as well as it can be used as a screening process for what could be the zoonoses that can survive in the various methods of food processing used in the community and or village. For example if they consume the meat raw, then we start looking at zoonoses that are spread through animal blood, those that survive as cysts in the animal flesh, those present in the bowels and animal excreta and so on.

Step 3:

Sanitation, which includes disposal of animal remains, proximity of people to their livestock, management of livestock and exposure to animal excreta (in case of leptospirosis) is also another important factor to consider if we can control zoonoses. This point puts emphasis on the fact that an infected animal carcass or any animal remains are still a source of zoonoses. Poor disposal can lead to spread of diseases.

From these three steps outlined it is crucial to have community involvement much earlier even before the onslaught of the diseases. If through surveillance, there is knowledge of the possible zoonoses that could affect a particular community, it is importantl to alert the community before hand and offer the necessary training and advice to avoid the spread of the diseases. Knowledge of day to day habits of a community can be a good start in communicating to the community of the lurking dangers with regard to animals and their products. Community leaders have a good connection as regards communication and execution of instructions within their communities. These leaders are therefore an important link between health/veterinary experts and the entire community. It is important to understand hierarchies within the communities as this is a crucial aspect in communicating with communities especially in rural areas.

Zoonoses and Man; Where can we find zoonotic diseases?

Human beings have always lived in close proximity with animals for centuries. Animals have been used as beasts of burdens on farms and households as well as a source of meat and animal products such as milk, eggs, meat and leather. Animal excreta has been used as a source of manure and biogas.

In as much as animals have always provided for man, they have also been a source of some of mans’ worst diseases some of which are curable and others incurable.

The diseases that are carried by animals and are passed on to humans are called zoonosis(es). Some of the modern diseases that started as zoonoses include:

·         Measles

·         Smallpox

·         Influenza

·         HIV

·         Diptheria

In my previous entry, I outlined zoonotic diseases by their causative agents and you will notice that the 5 diseases I have mentioned above including SARS, rabies, echirococcosis, taeniasis, brucellosis and trematodisis, are the major diseases that are of focus as public health threats.  But there are many more zoonotic diseases the world is not paying attention to and yet they are causing death  and becoming a public health issue. As such most zoonotic diseases are also known as neglected tropical diseases (NTDs).

Where are these zoonotic diseases found?

From the name neglected tropical diseases one could have a clue that these diseases mostly occur in the tropics. They are commonly found in Latin America, South East Asia and part of the Congo basin.

Below is the list of countries where NTDs are a major problem;

Americas and Latin America	South East Asia	Africa
Mexico	India	Cameroon
Colombia	Vietnam	Tanzania
Ecuador	Laos	Congo- DRC
Peru	Bangladesh	Uganda
Bolivia	Cambodia
Peru	Thailand
Brazil	Malaysia
Venenzuela
USA

Outbreaks of zoonotic diseases have occurred in different parts of the world but the countries mentioned above have experienced some of the major outbreaks or have frequent outbreaks of zoonoses.

It is interesting to note that the countries that are mentioned in the table above have something in common, close proximity to rainforests. Is there any association between zoonoses and proximity to rainforests? From the map (

www.healthmap.org/predict/) I noticed that most of the zoonotic oubreaks occured in countries where there is a rainforest. In Africa, the Congo basin host the second largest rainforest in the world, the Congo rainforest, which encompasses, Cameroon, Congo-DRC and Equatorial guinea. While in Latin America, the countries affected by zoonoses host the worlds largest rainforest, the Amazon rainforest. In South East Asia, Malaysia and Indonesia also have some raiforests.

 

One important thing to note is that the rainforests of Africa, South East Asia and its associated archipelagos, and tropical America they match in their animal and plant diversity.

 

So what are the animals that are shared bewteen these rainforests which could be major carriers of zoonotic diseases?

 

Below is a list of animals associated with zoonotic diseases, I beleive one will be able to pack out some animals that are associated with rainforests.

 

Higher Mammals	Other mammals	Birds	Others
Cattle	Bats	Geese	Ticks
Chimpanzees	Hamsters	Chickens	Snails
Humans	Hyraxes		Mosquitoes
Gorillas	Oppossum		Fleas
Monkeys	Rabbits and hares		Flies
Dogs	Raccoons		Lice
Cats	Rats		Assasin bugs
Horses
Pigs
Sheep
Sloth
Wolves

In my next entry I will discuss further some of the major zoonotic outbreaks in the world and what is being done to control this emerging public health issue.

References

www.healthmap.org/predict/

 

Zoonoses

For the past month I have been writing on various infectious diseases that are affecting our world today.

In my entry today I will continue on our topic of infectious diseases and we are going to look at what are known as zoonoses.

First of all let us start by defining the word Zoonosis (plural- Zoonoses). Zoonosis is any disease or infection that is naturally transmissible from vertebrate animals to humans. Zoonoses are diseases of interest to humans  as humans have for centuries interacted with animals both wild and domesticated. Zoonoses can be transmitted through animal excreta, urine, and animal products.

Over 200 zoonoses have been described so far and atleast 61% of all human pathogens are zoonotic.  The big question is still what causes zoonoses?

Zoonoses are caused by various agents including:

·         Bacteria

·         Parasites

·         Fungi

·         Viruses

·         Unconventional agents

Let us break down some of the zoonotic diseases by their causative agents.

1.    Zoonoses caused by Bacteria

·         Salmonellosis

·         Campylobacteriosis

·         Anthrax

·         Brucellosis

·         Leptospirosis

·         Plague

·         Q-fever

·         Shigellosis

·         Tularaenia

2.    Zoonoses caused by Parasites

·         Cysticercosis/Taeniasis

·         Trematodosis

·         Echinococcosis

·         Toxoplasmosis

·         Trichinellosis

3.    Zoonoses caused by viruses

·         Rabies

·         Avian flu (bird flu) H5N1

·         Crimean- Congo hemorrhagic fever

·         Ebola

·         Rift valley fever

4.    Unconventional agents

·         These are agents that are yet to be defined for example the agent that causes spongiform encephalopathy the same variant that causes variant Cruetzfeldt-Jakob disease (vCJD).

In the coming weeks I will be looking at how zoonoses have affected communities, the efforts that have been put forward to overcome these zoonoses and the way forward.